by Greg Mayer
While Jerry’s photos of the fabulous wildlife in the Galapagos show us the marvels of life there, one thing that stood out to me when I visited the Galapagos was how frequently we came across dead animals, much more frequently than anyplace else I’ve been. This observation inspired two thoughts. First, could this abundant evidence of the struggle for existence have influenced Darwin? And, second, might the prevalence of carcasses be due to a dearth of scavengers in the depauperate biota of these islands?
On the mainlands of the Americas, there is no dearth of scavengers, two familiar ones being the Turkey Vulture (Cathartes aura) and the Black Vulture (Coragyps atratus), both found throughout the Neotropics and, for varying distances, into the United States (both) and Canada (Turkey only). Here are both of them, more or less in action.
This Turkey Vulture is standing next to a deceased Virginia Opossum (Didelphis virginiana) on a sidewalk in Oviedo, Florida.
These two Black Vultures are feeding on the carcass of a Nine-banded Armadillo (Dasypus novemcinctus), also in Oviedo, Florida. (Both of the scavenged species, opossum and armadillo, are more or less recent recent invaders from the south; the Black Vulture, too, is moving north.)
And here they are in action:
The Galapagos have one large raptorial bird, the Galapagos Hawk (Buteo galapagoensis), an insular derivative of Swainson’s Hawk (Buteo swainsoni). Although it hunts and eats a variety of prey, both small vertebrates and largish invertebrates, it also eats quite a bit of carrion. Darwin, in fact, thought it rather resembled caracaras, a group of hawk-like falcons that are largely scavengers, especially in its habits:
When a tortoise is killed even in the midst of the woods, these birds immediately congregate in great numbers, and remain either seated on the ground, or on the branches of the stunted trees, patiently waiting to devour the intestines, and to pick the carapace clean, after the meat has been cut away.
Jackson (1985:177) concurs:
… on every island they are also major scavengers. They will feed on virtually any dead animal. I have seen them at the carcasses of sea lions, marine iguanas, seabirds and even fish … They seem to be very fond of goat meat. … On one occasion, within five minutes of a goat being killed, thirteen birds arrived and sat within 5 m of myself and the carcass. [Invasive goats were/are being eradicated in the Galapagos by hunters employed for the purpose.]
The Galapagos Hawk, apparently, fills part of the scavenging niche filled by vultures on the mainland. It has disappeared from some islands since settlement, so its decline may account for the frequency of unscavenged carcasses. The generally dry conditions at sea level, which lead to rapid mummification, may also lead to a proliferation of unscavenged carcasses, so that Darwin, even before the hawk’s decline, may have come across them as well. I’ll have to query Jerry as to his observations in this regard.
Jackson, M.H. 1985. Galapagos: A Natural History Guide. University of Calgary Press, Calgary.
I’ve never been to Galapagos, but my vicarious observation is there is an unbelievable abundance of life concentrated in a small area. Perhaps another factor is life’s ubiquity which accounts for the over abundance of carcasses.
Though I believe the most important factor is your “dearth of scavengers” observation.
Interesting observation. I would have expected rats to scavenge as well, & perhaps sarcophgoys flies, but I suppose there are few beetles,so no corose burying beetles? Ih, what about the iguanas – are they all plant browsers (like marine iguanas)?
Are there any rats in the Galapagos?
SARCOPHAGOUS! Where is yhe edit?!
I’ve never been to the Galapagos, but I DID live in Oviedo about 20+ years ago, and there were definitely a fair few black vultures and turkey vultures there (And all throughout central Florida). I remember once seeing a single bald eagle fending off about 7 black vultures from the carcass of a dead raccoon. It was quite a spectacle.
In my part of NJ (central rural, farming), turkey vultures have mostly disappeared over the last twenty years, black vultures being much more prominent. Being me, I take photos of roadkill (lots of raccoons, possums, squirrels, and predominantly antlered rats— sorry, deer) and the scavengers that consume them. I usually have several cameras out to catch as much of the cycle as I can, when I can place them near fresh kills
The mention of the efforts to eradicate the goats on the islands brings up the clever method of using “Judas goats” to lure them to where hunters can do what needs to be done. https://locallyforeign.ca/2022/03/06/ecuador-project-isabela-and-the-judas-goat/
Interesting, thanks Mark. (And Greg, too.)
Bring back the wolves!
“Deceased” is politically correct for “dead” ? I know we are all related to this possum, but we were not that close.
If a Norwegian Blue can be deceased, I see no problem.
At least Greg didn’t say “an opossum that has passed”
“It is an EX-POSSUM!”
Hope those vultures don’t catch leprosy from the armadillo! (Did you know that the nine-banded armadillo is the best animal model for leprosy? They are rather susceptible to it.)
As for local carrion birds, I’m still feeding crows each day, mostly with peanuts. But since my Boss (she’s a vegetarian) is away, this week I roasted a short sirloin of lamb, and it didn’t take long for them to fly off with the section of lumbar spine, which surprised me as it probably weighed a pound. I often laugh at myself feeding these cheeky and friendly monsters, as in a previous life I did my best to shoot as many as I could for the sake of our lambs. It’s horrible what they do to a newborn lamb, or indeed a ewe having difficulties with her labour. Better to shoot a crow than a sheep. Funny how ethics are situational sometimes.
THERE ARE RATS everywhere In the world pretty much – invasive.